The release comes a week later than Torvalds would have liked, though he seemed more concerned with people trying to "game the system" than with the slight delay.
Image Source: Flickr (LuChOeDu)
"So the last week was much quieter than the preceding ones, which makes me suspect that one reason -rc7 was bigger than I liked was that people were gaming the system and had timed some of their pull requests for just before the release, explaining why -rc7 was big enough that I didn't actually want to do a final release last week. Please don't do that," Torvalds stated in his official announcement.
There's quite a bit that's new and/or improved in Linux 3.9, including improved support for the F2FS (Flash Friendly File System) file system for Samsung developers, improved ARM support, a Zero-Power optical device driver, audio and sound improvements, initial support for AMD Radeon HD 8000 Series graphics cards, better power management, faster LZO compression, experimental RAID 5/6 support for the Btrfs file system, and more.